Anatomy of the Upper Limb (Arm and Hand)

Overview

• The upper limb consists of 30 different bones.
• Components include:
  • The humerus (largest and longest bone of the upper limb)
  • The radius and ulna (forearm bones)
  • Carpal bones, metacarpals, and phalanges (hand and fingers)

The Humerus

• Largest and longest bone in the upper limb.
• Located in the upper portion of the arm.
• Features two curved surfaces at the elbow joint:
  • Capitulum (lateral surface) articulates with the radius.
  • Trochlea (medial surface) articulates with the ulna.

Forearm Bones

• Radius:
  • Located laterally in the anatomical position (further from the trunk).
• Ulna:
  • Located medially in the anatomical position (closer to the trunk).

Radioulnar Joints

• Proximal Radioulnar Joint:
  • Located near the elbow.
• Distal Radioulnar Joint:
  • Located near the wrist.
• Interosseous Membrane:
  • Dense fibrous tissue between the radius and ulna.
  • Maintains a fixed distance and distributes load between the bones.

The Wrist and Hand Bones

• Radiocarpal Joint:
  • Formed between the radius and three carpal bones (scaphoid, lunate, triquetrum).
• Carpal Bones (Total: 8):
  • Proximal row: Scaphoid, Lunate, Triquetrum, and Pisiform.
  • Distal row: Trapezium, Trapezoid, Capitate, and Hamate.

Metacarpals and Phalanges

• Metacarpals:
  • Total of 5, numbered I to V (from thumb to little finger).
• Phalanges:
  • The thumb (pollex) consists of 2 phalanges (proximal and distal).
  • Fingers 2-5 each have 3 phalanges (proximal, middle, and distal).